How to include a URL in the URL

I have a special controller in my app that is basically an out-gate to capture links leaving the app. A typical URL would look like: /_/out/https%3A%2F%2Fmyserver.com%2Fevents%2F.

I have the route set up properly - I know this because if I go to /_/out/blah-blah-blah, I get the expected output from the controller action.

With this URL though: /_/out/https%3A%2F%2Fmyserver.com%2Fevents%2F, all I get is the default

The requested URL /_/out/https://myserver.com/events/ was not found on this server.

404 error page. It's not the usual one from my app, but just the default Apache error page.

In Volt, I'm generating these URLs with: <a href = "/_/out/{{ url|url_encode }}">. I'm not sure if the problem lies with how I'm encoding the url, or with something in my .htaccess file, which is below:

I've actually come to the realization that I don't need to escape anything. I should be able to have my URL look like: /_/out/https://myserver.com/events/. The only trouble is in my route, :params will cause the action parameters to be split at each /, rather than leaving it as just one string. So now I think this is a regex problem.